High-velocity discharge equalizing system and method

ABSTRACT

According to one embodiment of the invention, a high-velocity fluid discharge device includes tubing having one or more orifices formed therein, a shroud coupled to the tubing such that, when a fluid flowing through the tubing exits the orifices, the fluid impinges on an inside surface of the shroud, and openings at both ends of the shroud. The openings have substantially the same areas.

BACKGROUND

The present invention relates generally to wellbore productionenhancement operations and, more particularly, to a high-velocitydischarge equalizing system and method.

Various procedures have been utilized to increase the flow ofhydrocarbons from subterranean formations penetrated by wellbores. Forexample, a commonly used production enhancement technique involvescreating and extending fractures in the subterranean formation toprovide flow channels therein through which hydrocarbons flow from theformation to the wellbore. The fractures are created by introducing afracturing fluid into the formation at a high flow rate and highpressure in order to exert a sufficient force on the formation to createand extend fractures therein. Solid fracture proppant materials, such assand, are commonly suspended in the fracturing fluid so that uponintroducing the fracturing fluid into the formation and creating andextending fractures therein, the proppant material is carried into thefractures and deposited therein, whereby the fractures are preventedfrom closing due to subterranean forces when the introduction of thefrac fluid ceases.

In the line that transports the fracturing fluid from the pumps to thewellhead, there is typically a pipe tee that facilitates the use of areturn line that transports fluid to a pit or other fluid containmentwhen so desired. A valve that controls flow through this additional linemay be inadvertently opened during high-flow and high-pressuresituations, such as hydraulic fracturing. This may cause the energizedfluid flowing through the line to surge out through the end, which maycreate undesirable reaction forces that cause the line to moveuncontrollably. Anchors are sometimes used to minimize movement of theline.

SUMMARY

According to one embodiment of the invention, a high-velocity fluiddischarge device includes tubing having one or more orifices formedtherein, a shroud coupled to the tubing such that, when a fluid flowingthrough the tubing exits the orifices, the fluid impinges on an insidesurface of the shroud, and openings at both ends of the shroud. Theopenings have substantially the same areas.

Some embodiments of the invention provide numerous technical advantages.Some embodiments may benefit from some, none, or all of theseadvantages. For example, according to certain embodiments, high-flowdischarge of fluid due to an inadvertent opening of a valve on the linerunning to a pit or fluid containment during hydraulic fracturing orother high pressure operations may be equalized so as to avoid excessivemovement of the end of the line, which leads to a safer environment. Insome embodiments, a shield may be utilized with such an equalizingsystem to prevent exiting fluids from throwing projectiles on locationas well as provide additional anchorage into the ground.

The features and advantages of the present invention will be readilyapparent to those skilled in the art upon a reading of the descriptionof the exemplary embodiments that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial plan view of a production enhancement systemutilizing a high-flow discharge equalizing device in accordance with oneembodiment of the present invention;

FIG. 2 is a cross-sectional view of the equalizing device of FIG. 1 inaccordance with one embodiment of the present invention; and

FIGS. 3A and 3B are perspective views of an equalizing device inaccordance with another embodiment of the present invention.

DESCRIPTION

FIG. 1 is a partial plan view of a production enhancement system 100utilizing a high-flow discharge equalizing device 200 in accordance withone embodiment of the present invention. In the illustrated embodiment,system 100 is being utilized to perform a hydraulic fracturingoperation; however, system 100 may be utilized for any suitable wellstimulation treatment or production enhancement operation in which fluidis circulated through a well (not illustrated).

System 100 includes one or more pumps 102 that deliver a fracturingfluid or other suitable fluid to a wellhead 104 via delivery line 106having an associated valve 107. Because of the nature of hydraulicfracturing, the fluid is typically a high-flow, high-pressure fluid. Inone embodiment, the fluid is flowing at a pressure of at least 100 psiand may be a gas, homogeneous foam, a liquid, or co-mingled fluid andgas. System 100 also includes a discharge line 108 having an associatedvalve 109 that is utilized to deliver fluid to a pit 110, which may beany suitable fluid containment, when so desired.

According to the teachings of one embodiment of the invention, system100 includes discharge equalizing device 200 that creates apressure-balanced exit condition for the fluid flowing out of the openend of discharge line 108 into pit 110. Details of discharge equalizingdevice 200 are described in further detail below in conjunction withFIG. 2.

Discharge equalizing device 200 may also include a shield 208 to shieldany exiting fluids flowing out of discharge equalizing device 200 andalso to serve as a restraint system by anchoring discharge equalizingdevice 200 into the ground. Although not illustrated, additionalanchorage systems may be associated with discharge line 108 foranchoring discharge line 108 into the ground.

FIG. 2 is a cross-sectional view of discharge equalizing device 200 inaccordance with one embodiment of the invention. In the illustratedembodiment, discharge equalizing device 200 includes a tubing 202 havinga plurality of orifices 203, a shroud 204, a reinforcing pad 206, andshield 208.

Tubing 202 may be any suitable conduit operable to transport a fluidtherethrough. Tubing 202 may be any suitable size and shape and may beformed from any suitable material. In one embodiment, tubing 202 has adiameter between approximately two and three inches. The fluid flowingthrough tubing 202 flows in the direction of arrow 210 and escapes fromtubing 202 through orifices 203, as indicated by arrows 211. Orifices203 may be any suitable size and there may be any suitable number oforifices 203. In one embodiment, there are multiple sets of orifices 203longitudinally spaced along tubing 202, with each set of orifices 203including a plurality of orifices equally spaced around a circumferenceof tubing 202. For example, orifices 203 may be spaced around thecircumference of tubing 202 at an angular spacing of 30°, 60°, 90°, or180° depending on the number of orifices in each set. Orifices 203 mayalso be offset from one another. The present invention contemplates anysuitable arrangement of orifices 203 formed in tubing 202.

In a particular embodiment of the invention, tubing 202 may have abuffer zone 212 associated with its downstream end in which there are noorifices. Buffer zone 212 thus facilitates the reduction of the fluidshock exiting orifices 203 by smoothing the transition from zeropressure to high pressure. In other words, as fluid starts exitingorifices 203 buffer zone 212 begins to fill up with fluid so that thefull pressure of the fluid does not immediately exit orifices 203, butinstead builds up progressively.

Shroud 204 couples to tubing 202 in any suitable manner. Shroud 204 maybe any suitable size and may be formed from any suitable material. Inone embodiment, shroud 204 is formed from ten inch casing; however,other suitable diameters may be utilized. In addition, shroud 204 mayhave any suitable length. In the illustrated embodiment, shroud 204couples to tubing 202 with an end cap 214 at the downstream end oftubing 202 and an entrance cap 216 at the upstream end. In order for thefluid existing in shroud 204 to exit shroud 204, end cap 214 includes adownstream opening 215 and entrance cap 216 includes an upstream opening217. Although both downstream opening 215 and upstream opening 217 mayhave any suitable open areas, downstream opening 215 and upstreamopening 217 have substantially the same open areas. This facilitates thepressure-balanced exit condition. In some embodiments, shroud 204 maynot be uniform, but may have openings along its length.

Because the fluid flowing through tubing 202 is flowing at highvelocity, and because orifices 203 have a relatively small diameter, agreat force may be exerted on an inside wall 218 of shroud 204. This maycause deterioration of the wall of shroud 204 depending on many factors,such as the thickness of shroud 204, the type of material shroud 204 isformed from, the type of fluid flowing through tubing 202, the velocityof fluid, and the size of orifices 203. Therefore, reinforcing pad 206may be coupled to an outside surface 220 of shroud 204 in a locationcorresponding to where the fluid impinges on inside surface 218.Reinforcing pad 206 may also couple to inside wall 218 of shroud 204 asa sacrificial insert. Reinforcing pad 206 may be any suitable size andshape, may be formed from any suitable material, and may couple toshroud 204 in any suitable manner. In lieu of reinforcing pad 206, thewall thickness of shroud 204 may be increased or the type of materialthat shroud 204 is formed from may be changed.

Shield 208 functions to act as a shield for any fluid exiting upstreamopening 217 of shroud 204, and may also act as an anchorage system fordischarge equalizing device 200 by imbedding a portion of shield 208into the ground. Shield 208 may be any suitable size and shape and maybe formed from any suitable material.

In operation of one embodiment of the invention, a high flow fluid flowsthrough tubing 202 in the direction of arrow 210. The fluid startsexiting orifices 203 and quickly fills up buffer zone 212 before thefull pressure of the fluid exiting orifices 203 starts impinging uponinside wall 218 of shroud 204 that counteracts the reaction forcegenerated by the exiting of the fluid through orifices 203. Fluid thenexits out downstream opening 215 and upstream opening 217 before beingdeposited into pit 110 (FIG. 1). The fluid flowing out of downstreamopening 215 and the fluid flowing out of upstream opening 217 createsubstantially equal but offsetting forces. This offsetting of forcescreates a pressure-balanced exit condition for discharge equalizingdevice 200 and prevents the end of discharge line 108 from movinguncontrollably. Therefore, a safer environment may be facilitated.

In another embodiment of the invention, illustrated in FIG. 3B, tubing302 is shown with equally spaced orifices 303 and no shroud 204 exists.In this embodiment, the fluid flowing through tubing 302 exits throughorifices 303, and since these orifices have equal open areas and equallyspaced, then the forces caused by the fluid flowing out of orifices 303offset each other, thereby facilitating a pressure-balanced exitcondition.

In another embodiment of the invention, which is not illustrated in thefigures, tubing 202 does not have orifices 203 formed therein and noshroud 204 exists. In this embodiment, a tee is coupled to the end oftubing 202 so that when the fluid flowing through tubing 202 exits theend orifice of tubing 202, it exerts a force on the inside of the teeand then flows out both ends of the main branch of the tee. If theseends of the tee have equal open areas, then the forces caused by thefluid flowing out of the ends offset each other, thereby facilitating apressure-balanced exit condition.

FIGS. 3A and 3B are perspective views of a discharge equalizing device300 in accordance with another embodiment of the present invention.Discharge equalizing device 300 is similar in function to dischargeequalizing device 200; however, discharge equalizing device 300 includesa collection tank 308 that supports both ends of a tubing 302. In theillustrated embodiment, discharge equalizing device 300 includes tubing302 having one or more orifices 303, a shroud 304, a pair of shields 306a, 306 b, a lifting eye 307, a removable plug 310, and collection tank308.

The description of tubing 302, orifices 303, and shroud 304 issubstantially similar to the discussion of tubing 202, orifices 203, andshroud 204 as found in FIG. 2 and, hence, is not described again.

Shields 306 a, 306 b, are also similar to shield 208 of FIG. 2; however,in the embodiment illustrated in FIG. 3A, shield 306 a is placedadjacent an upstream opening 317 of shroud 304 and shield 306 b isplaced adjacent a downstream opening 315 of shroud 304. Shields 306 a,306 b create a symmetry in discharge equalizing device 300 thatfacilitates the balancing of the resultant forces from fluid exitingupstream opening 317 and downstream opening 315.

The ends of tubing 302 may be coupled to collection tank 308 in anysuitable manner. Collection tank 308, along with lifting eye 307,facilitates the portability of discharge equalizing device 300. As such,discharge equalizing device 300 may be mounted on a truck, trailer, askid, or other suitable vehicle for easy transportation.

Although collection tank 308 may have any suitable size and shape, inone embodiment, collection tank 308 includes a top 314 disposedunderneath tubing 302 and shroud 304 to collect the fluids exitingshroud 304. In a particular embodiment, top 314 has a concave surface toassure that forces on collection tank 308 are downward. In any event,top 314 includes a plurality of drain holes 316 that direct the fluiddown into collection tank 308. Collecting fluid in collection tank 308also facilitates added weight to discharge equalizing device 300, whichaids in anchoring the device. A drain 318 may be coupled near a bottomof collection tank 308 to facilitate the draining of the fluid containedtherein.

As illustrated in FIG. 3B, tubing 302 may include a buffer zone 320 thatfunctions in a similar manner to buffer zone 212 of tubing 202 (FIG. 2).Removable plug 310 functions as a clean-out for tubing 302 and may beany suitable removable plug that couples to the downstream end of tubing302 in any suitable manner.

In operation of one embodiment of the invention illustrated in FIGS. 3Aand 3B, fluid having a high velocity flows through tubing 302 in thedirection as indicated by arrow 322. The fluid starts exiting orifices303 and eventually fills up buffer zone 320 before the full pressure ofthe fluid is exiting out orifices 303. The fluid impinges upon theinside surface 323 of shroud 304 and exits shroud 304 via downstreamopening 315 and upstream opening 317 before hitting shields 306 a and306 b. The fluid is then directed in all directions and some of thefluid collects on top 314 of collection tank 308. The fluid then drainsthrough drain holes 316 into collection tank 308 where it may be storedor drained off using drain 318. As described above, the fluid exitingorifices 303 exerts a force on the inside surface 317 of shroud 304 thatoffsets the reaction force generated by the fluid flowing out oforifices 303. This may create a pressure-balanced exit condition fortubing 302.

Although some embodiments of the present invention are described indetail, various changes and modifications may be suggested to oneskilled in the art. The present invention intends to encompass suchchanges and modifications as falling within the scope of the appendedclaims.

1. A fluid discharge device comprising: tubing having one or moreorifices formed therein; a shroud coupled to the tubing such that, whena fluid flowing through the tubing exits the orifices, the fluidimpinges on an inside surface of the shroud; and openings at both endsof the shroud, wherein the openings have substantially the same areas.2. The device of claim 1 further comprising a reinforcing pad coupled toa surface of the shroud in a location corresponding to where the fluidimpinges on the inside surface.
 3. The device of claim 1 wherein the oneor more orifices comprise a plurality of orifices equally spaced arounda circumference of the tubing.
 4. The device of claim 3 wherein theorifices are spaced around the circumference of the tubing at an angularspacing selected from the group consisting of 30 degrees, 60 degrees, 90degrees, and 180 degrees.
 5. The device of claim 1 wherein the one ormore orifices comprise a plurality of orifices spaced along a length ofthe tubing.
 6. The device of claim 1 wherein the tubing includes abuffer zone in which there are no orifices.
 7. The device of claim 1wherein the fluid is flowing at a pressure of at least 100 psi.
 8. Thedevice of claim 1 further comprising a shield coupled to an outsidesurface of, and surrounding, the tubing at a location upstream from theshroud.
 9. The device of claim 1 further comprising a pair of shieldscoupled to an outside surface of, and surrounding, the tubing, the pairof shields disposed adjacent opposite ends of the shroud.
 10. The deviceof claim 1 further comprising a selectively removable plug coupled to adownstream end of the tubing.
 11. A fluid discharge method comprising:receiving a fluid flow in a tubing; directing the fluid out through oneor more orifices of the tubing; impinging the fluid on an inside surfaceof a shroud surrounding the tubing; directing the fluid out through atleast two openings on opposite ends of the shroud; and using thereaction force caused by the fluid flowing out one of the openings tooffset a reaction force caused by the fluid flowing out of the otheropening to stabilize the tubing.
 12. The method of claim 11 furthercomprising collecting the fluid exiting the openings of the shroud. 13.The method of claim 11 further comprising causing the openings to havesubstantially the same area.
 14. The method of claim 11 furthercomprising reinforcing a surface of the shroud in a locationcorresponding to where the fluid impinges on the inside surface.
 15. Themethod of claim 11 wherein the fluid is flowing at a pressure of atleast 100 psi.
 16. The method of claim 11 further comprising anchoringthe tubing into the ground.
 17. A fluid discharge device comprising:tubing having a plurality of orifices spaced around a circumference ofthe tubing; a shroud coupled to the tubing such that, when a fluidflowing through the tubing exits the orifices, the fluid impinges on aninside surface of the shroud; openings at both ends of the shroud,wherein the openings have substantially the same areas; a pair ofshields coupled to an outside surface of, and surrounding, the tubing,wherein the pair of shields are disposed adjacent opposite ends of theshroud; and a collection tank disposed below the shroud and operable tocollect the fluid exiting the opposite ends of the shroud, wherein thecollection tank supports opposite ends of the tubing.
 18. The device ofclaim 17 further comprising a reinforcing pad coupled to a surface ofthe shroud in a location corresponding to where the fluid impinges onthe inside surface.
 19. The device of claim 17 wherein the orifices areequally spaced around the circumference of the tubing.
 20. The device ofclaim 17 wherein the orifices are spaced along a length of the tubing.21. The device of claim 17 wherein the tubing includes a buffer zone inwhich there are no orifices.
 22. The device of claim 17 wherein thefluid is flowing at a pressure of at least 100 psi.
 23. The device ofclaim 17 further comprising a selectively removable plug coupled to adownstream end of the tubing.
 24. The device of claim 17 wherein thecollection tank includes a drain coupled near a bottom of the collectiontank.
 25. The device of claim 17 wherein the collection tank includes aconcave top with a plurality of drain holes.
 26. A fluid dischargemethod comprising: receiving a fluid flow in a tubing; directing thefluid out through at least two orifices equally spaced around acircumference of the tubing; and using the reaction force caused by thefluid flowing out at least one of the orifices to offset the reactionforce caused by the fluid flowing out an opposite orifice to stabilizethe tubing.